A Cartridge for a Vapour Generating System

ABSTRACT

A cartridge for a vapour generating system, such as an e-cigarette, includes a vaporization chamber in which liquid is vaporized from a heater surface to mix with a flow of air through the vaporization chamber. Before reaching an air outlet, the airflow must pass through a restriction means such as a narrow neck, which helps to prevent droplets of re-condensed liquid leaking out of the air outlet. The restriction means also provides a convenient way to determine the distribution of air pressure along the airflow path and the overall resistance to draw of the vapour generating system.

TECHNICAL FIELD

The present disclosure relates generally to a cartridge for a vapour generating system configured to heat a liquid to generate a vapour which cools and condenses to form an aerosol for inhalation by a user of the system. The present disclosure also relates to a vapour generating system that comprises a vapour generating device and a cartridge configured to be used with the vapour generating device.

TECHNICAL BACKGROUND

The term vapour generating system (or more commonly electronic cigarette or e-cigarette) refers to handheld electronic apparatus that is intended to simulate the feeling or experience of smoking tobacco in a traditional cigarette. Electronic cigarettes work by heating a vapour generating liquid to generate a vapour that cools and condenses to form an aerosol which is then inhaled by the user. Accordingly, using e-cigarettes is also sometimes referred to as “vaping”. The vapour generating liquid usually comprises nicotine, propylene glycol, glycerine and flavourings.

Typical e-cigarette vaporizing units, i.e. systems or sub-systems for vaporizing the vapour generating liquid, utilize a heating element to produce vapour from liquid stored in a capsule, tank or reservoir. When a user operates the e-cigarette, liquid from the reservoir is transported through a liquid transfer element, e.g. a cotton wick or a porous ceramic block, and is heated by the heating element to produce a vapour, which cools and condenses to form an aerosol that can be inhaled. To facilitate the ease of use of e-cigarettes, removable cartridges are often employed. These cartridges are often configured as “cartomizers”, which means an integrated component comprising a liquid store, a liquid transfer element and a heater. Electrical connectors may also be provided to establish an electrical connection between the heating element and a power source. Such cartridges may be disposable, i.e. not intended to be capable of reuse after the supply of liquid in the reservoir has been exhausted. Alternatively, they may be reusable, being provided with means allowing the reservoir to be refilled with a new supply of vapour generating liquid. Particularly in the case of disposable cartridges, it is desirable to reduce the number and complexity of their components, thereby reducing waste and making the manufacturing process simpler and cheaper.

A cartridge for an e-cigarette typically comprises an air inlet at a first end and an air outlet at a second, opposite end. (Considered from the viewpoint of a user of the system, the first end of the cartridge may also be termed the distal end and the second end of the cartridge may also be termed the proximal end or mouth end.) The first end of the cartridge is configured to be releasably connected to the vapour generating device, which may, for example, contain a power source and control electronics. A user inhales through a mouthpiece at the second end of the cartridge to draw air along an airflow path from the air inlet to the air outlet. The airflow path passes through a vaporization chamber, where liquid vaporized by the heating element mixes with the air.

In order to allow time for the vapour to cool and condense into an aerosol before it reaches the second end of the cartridge, the vaporization chamber is typically located at the first end of the cartridge, close to the air inlet. The reservoir of vapour generating liquid may therefore be located towards the second end of the cartridge and be separated from the vaporization chamber by a generally transverse wall. (In this specification, “longitudinal” refers to the direction extending from the first end to the second end of the cartridge, parallel to the central axis of the cartridge if there is one, and “transverse” refers to any plane or direction that is generally perpendicular to the longitudinal direction.) The liquid transfer element allows liquid to pass from the reservoir to the vaporization chamber through the transverse wall. Therefore, if the liquid transfer element is in the form of a permeable sheet or block, it is typically set into the transverse wall with a similarly transverse orientation. In particular, the liquid transfer element presents a transverse surface in the vaporization chamber, on which heated liquid is exposed to the air in the chamber in order to vaporize and mix with the air in the chamber.

In many prior e-cigarettes, the air inlet is located centrally in the first end of the cartridge. (The location of the air inlet may be determined by the design of the vapour generating device, to which the first end of the disposable cartridge is connected.) The vaporization chamber is also located centrally in the cartridge, close to the first end, whereby air entering the air inlet in the longitudinal direction flows directly into the vaporization chamber. This can give rise to two problems.

First, the direct airflow path from the air inlet to the vaporization chamber provides a direct channel for condensed liquid to leak out of the vaporization chamber in the opposite direction and emerge from the air inlet. Such leaked liquid may reach the exterior of the vapour generating system and be unsightly or otherwise unacceptable to the user. Additionally or alternatively, it may find its way into the vapour generating device and there cause damage to the power source or the control electronics. Leakage from the air outlet can also occur and is similarly undesirable.

The second problem is that, if the liquid transfer element presents a transverse heated surface in the vaporization chamber, as previously described, then air entering the chamber in the longitudinal direction impinges perpendicularly on that surface. This results in a concentrated airstream at one point on the surface, whereas it would be preferable to achieve vaporization of liquid into the air evenly across the whole area of the surface.

SUMMARY OF THE INVENTION

The invention provides a cartridge for a vapour generating system, the cartridge comprising a first end and a second end together defining a longitudinal direction from the first end to the second end; an air inlet; an inlet channel; a vaporization chamber; an outlet channel; and an air outlet; wherein an airflow path extends from the air inlet through the inlet channel to the vaporization chamber, then through the outlet channel to the air outlet; the cartridge further comprising restriction means for restricting airflow between the outlet channel and the air outlet.

The invention further provides a vapour generating system, which comprises such a cartridge releasably connected to a vapour generating device.

The restriction means in the cartridge according to the invention offers one or more of the following advantages:

-   -   If droplets of liquid have condensed on the walls of the outlet         channel, it helps to prevent them flowing to the air outlet.     -   It also serves to determine the pressure distribution along the         airflow path.     -   It plays a significant role in determining the overall         “resistance to draw” of the vapour generating system.

The restriction means is preferably a neck in the airflow path, a cross-sectional area of the neck being smaller than a cross-sectional area of the outlet channel. It is preferred that the cross-sectional area of the neck should in fact be smaller than a cross-sectional area anywhere else along the airflow path. The reduced cross-sectional area of the neck offers resistance to the flow of air towards the air outlet. It is easy to manufacture and is less likely to become blocked than, for example, a restriction means formed by a mesh placed across the airflow path.

The neck is preferably oriented such that the airflow through it is in a transverse direction. This change of direction from the generally longitudinal outlet channel offers a further hindrance to drops of condensed liquid in the outlet channel that might leak from the air outlet.

The air outlet may be located in the second end of the cartridge. This is a convenient location for the air outlet to be used directly as a mouthpiece of the vapour generating system or to deliver air to a separate mouthpiece that may be located at the second end of the vapour generating system. An air outlet in the end of the cartridge must have at least a component of its airflow in the longitudinal direction. If the airflow through the neck is generally in the transverse direction, this provides a further change of direction and further hinders the passage of droplets of condensation that might leak from the air outlet.

Preferably the cartridge further comprises, between the restriction means and the air outlet, a lip that projects from the second end towards the first end. The lip may be part of a collar that surrounds the air outlet. Such a lip or collar still further hinders the passage of droplets of condensation that might leak from the air outlet.

The cartridge typically further comprises a reservoir configured to store vapour generating liquid to be vaporized in the vaporization chamber. Preferably the outlet channel is disposed in the cartridge so that it does not intersect the reservoir. For example, the outlet channel may be disposed adjacent to a longitudinal side wall of the cartridge, rather than conventionally following a central axis of the cartridge. This avoids the need for a gasket, which would otherwise have to be provided to seal around the outlet channel where it enters the reservoir.

Further preferred aspects of the invention relate to the inlet channel of the cartridge, which leads from the air inlet to the vaporization chamber.

The airflow path through the inlet channel preferably follows a first transverse direction then turns to enter the vaporization chamber in a second transverse direction. Additionally or alternatively, the inlet channel is convoluted such that it provides no straight path from the air inlet to the vaporization chamber. For example, the inlet channel may comprise at least two right-angled bends between the air inlet and the vaporization chamber. Each of these features entails changes in direction along the length of the inlet channel, whereby, if droplets of condensed or unvaporized vapour generating liquid have collected in the vaporization chamber, those droplets are hindered from flowing towards and leaking out of the air inlet, at least as long as the vapour generating system remains held in a generally constant orientation.

An airflow diverter element may be disposed in the inlet channel, whereby a first surface of the diverter element defines the first transverse direction and a second, opposite surface of the diverter element defines the second transverse direction. The first transverse direction may thus be opposite to the second transverse direction.

Preferably, the airflow path through the air inlet is substantially parallel to the longitudinal direction. This ensures that there is a further change of airflow direction between the air inlet and the first transverse part of the inlet channel. It allows the air inlet to be conveniently located centrally in the first end of the cartridge.

A cartridge according to the invention may further comprises a heater surface in the vaporization chamber that is substantially transverse to the longitudinal direction. Preferably the airflow path through the vaporization chamber is substantially parallel to the heater surface to encourage substantially uniform evaporation of the vapour generating liquid from all parts of the surface.

The heater surface may be a distal surface of a ceramic heating element and may comprise a heating track that extends between two electrical connection points. In preferred embodiments of the invention, the cartridge further comprises two electrical terminals that are exposed to the exterior of the cartridge and respectively contact the two electrical connection points. Thereby, the use of loose wires is avoided and the manufacturing process becomes simpler and more reliable.

The cartridge is intended for use in a vapour generating system configured to heat a vapour generating liquid within the cartridge to volatise at least one component of the vapour generating liquid and thereby generate a vapour which cools and condenses to form an aerosol for inhalation by a user of the vapour generating system.

The vapour generating liquid may, for example, comprise polyhydric alcohols and mixtures thereof such as glycerine or propylene glycol. The vapour generating liquid may contain nicotine.

In general terms, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air or another gas. It should, however, be noted that the terms ‘aerosol’ and ‘vapour’ may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section through a cartridge according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view of the cartridge of FIG. 1 .

FIG. 3 is a schematic diagram of a vapour generating system that comprises a cartridge in accordance with the present invention.

The cartridge 2 illustrated in the drawings has a generally rectangular shape, with a longitudinal axis 4 extending between a first end 6 and a second end 8 of the cartridge 2. As seen in this embodiment, the cartridge 2 need not be symmetrical about the axis 4. The first end 6 of the cartridge 2 is provided with connection means 10 for clipping or otherwise releasably connecting the cartridge 2 to the vapour generating device 11 which may, for example, contain a power source 50 and control electronics 52.

The second end 8 of the cartridge is substantially occupied by a reservoir 20, which stores a vapour generating liquid. In the centre of the first end 6 of the cartridge 2, there is formed an air inlet 12. It may be assumed that when the cartridge 2 is connected to the vapour generating device 11, air is still able to flow from the surrounding atmosphere to the air inlet 12, for example through one or more air passages (not shown) formed in the vapour generating device 11. The air inlet 12 communicates with an inlet channel 14, which leads to a vaporization chamber 22 (described below). In or near the centre of the second end 8 of the cartridge, there is formed an air outlet 16. An outlet channel 17 leads from the vaporization chamber 22 to the air outlet 16. Because the vaporization chamber 22 is located near the first end 6, the outlet channel 17 conducts air over the majority of the length of the cartridge 2 from the first end 6 to the second end 8. The outlet channel 17 is offset laterally from the axis 4 to follow one of the longitudinal side walls 18 of the cartridge housing 15 and pass to one side of the reservoir 20.

A separate mouthpiece 19 (seen in FIG. 3 ) can be releasably connected to the second end 8 of the cartridge. In some embodiments, the second end 8 of the cartridge 2 itself can act as a mouthpiece, in the sense that a user can engage their lips directly with the second end 8 of the cartridge 2. The mouthpiece 19 is in fluid communication with the air outlet 16 so that, by sucking on the mouthpiece 19, a user of the vapour generating system can draw air through the cartridge 2. The air follows a continuous airflow path extending from the air inlet 12 at the first end 6, successively through the inlet channel 14, the vaporization chamber 22 and the outlet channel 17, to the air outlet 16 and the optional mouthpiece 19 at the second end 8.

A gasket 24 rests on a seat 21 within the cartridge housing 15 and separates the reservoir 20 at the second end 8 of the cartridge 2 from the vaporization chamber 22 at the first end 6. The gasket 24 is applied during manufacture to close the reservoir 20 after it has been filled with vapour generating liquid. If the reservoir 20 is designed to be refillable, then the gasket 24 must be capable of removal to admit a new supply of liquid into the reservoir 20. The gasket 24 engages the inner wall of the reservoir 20 to form a seal that prevents leakage of the vapour generating liquid from the reservoir 20. Because the outlet channel 17 is offset laterally and does not pass through the reservoir 20, it is not necessary to provide a second gasket to seal around the channel 17. The illustrated embodiment of the invention therefore enables a reduced number of components and a simpler manufacturing process compared with the prior art.

A ceramic block 26 is set into the gasket 24 such that its distal surface 28 is transversely aligned and is exposed to the vaporization chamber 22. An opposite, proximal surface 29 of the ceramic block 26 is exposed to the liquid in the reservoir 20. The ceramic block 26 is porous and acts as a liquid transfer element to transport liquid, as indicated by arrow 31, from the reservoir 20 to the distal surface 28, where the liquid is exposed to the vaporization chamber 22.

An electrically conductive heating track 30 is printed on the distal surface 28 of the ceramic block 26, which therefore may also be termed a heater surface. The heating track 30 extends between a pair of electrical connection points 32. The respective electrical connection points 32 are contacted by the proximal ends of a pair of electrical terminals 34. The distal ends of the electrical terminals 34 are exposed to the exterior of the cartridge 2. Specifically, they are exposed on the first (distal) end 6 of the cartridge 2 to provide an electrical connection from the heating track 30 to a power source 50 contained within the vapour generating device 11. When a voltage is applied between the electrical terminals 34, current flows through the heating track 30 and resistive heating raises the temperature of the heater surface 28 of the ceramic block, thereby causing liquid to vaporize from the surface 28 into the airstream that passes through the vaporization chamber 22. An airflow sensor (not illustrated) may be used to detect when air is moving along the airflow path, whereby a control circuit 52 in the vapour generating device 11 can conserve energy by supplying power to the heating track 28 only when a user is inhaling though the system. The airflow sensor may be located in the vapour generating device 11 to detect when air is moving along an air passage that leads to the air inlet 12. The electrical terminals 34 are preferably constructed as rigid elements that can be brought into contact with the electrical connection points 32 of the heating track 30 during assembly of the system. Thereby, the use of loose wires is avoided and the manufacturing process becomes simpler and more reliable. The electrical terminals 34 may be embedded in an end cap 36 of the cartridge 2. An end cap gasket 37 forms an airtight seal between the end cap 36 and the cartridge housing 15 to ensure that air cannot enter the cartridge 2 except by following the intended airflow path from the air inlet 12.

Because the air inlet 12 is aligned with the axis 4, air is drawn into the air inlet 12 in the longitudinal direction. In this embodiment the vaporization chamber 22 also lies on the axis 4 so, if the air from the inlet 12 were permitted to continue in a straight path, it would enter directly into the vaporization chamber 22 in the longitudinal direction. However, the air that flows from the inlet 12 is forced instead to follow a convoluted path through the inlet channel 14, which results in it entering the vaporization chamber 22 along the transverse direction, parallel to the heater surface 28. Specifically, a diverter element 38 extends transversely between the air inlet 12 and the vaporization chamber 22 to divert the airflow away from its longitudinal direction at the air inlet 12. Other methods of forcing the air to follow a convoluted path will be readily apparent, including forming the diverter element 38 integrally with the end cap 36 or with the main body of the cartridge 2.

The airflow diverted from the air inlet 12 is indicated by arrows 40. It initially travels in a first transverse direction (to the right as viewed in FIG. 1 ), following a distal surface of the diverter element 38 and (in this embodiment) passing around one of the electrical terminals 34. After reaching the extremity of the diverter element 38, the airflow reverses and follows a proximal surface of the diverter element 38, travelling in a second transverse direction (to the left as viewed in FIG. 1 ) that is opposite to the first transverse direction. The airflow again passes around one of the electrical terminals 34 to enter the vaporization chamber 22 in the second transverse direction. Because the airflow through the vaporization chamber 22 is parallel to the heater surface 28, it affects all parts of the heater surface 28 equally and gives rise to substantially even vaporization of liquid across the whole area of the surface 28. The airflow preferably exits from the vaporization chamber 22 opposite to its entry point, then follows the outlet channel 17 towards the second end 8 of the cartridge 2. During the passage of the air along the outlet channel 17, there is time for it to cool and for the liquid vapour it carries to condense into droplets before the resulting aerosol is inhaled by the user.

Liquid can sometimes collect in the vaporization chamber 22, either because liquid presented on the heater surface 28 fails to vaporize fully or because liquid that has vaporized subsequently re-condenses on the internal walls further along the airflow path and flows back to the vaporization chamber 22. It is desirable to prevent the collected liquid leaking out of the cartridge 2. Preferably, the inlet channel 14 should be sufficiently convoluted that there exists no straight path from the air inlet 12 to the vaporization chamber 22, along which liquid from the vaporization chamber 22 might easily leak out of the air inlet 12. This can be achieved by forming the inlet channel 14 with a single bend, provided the values of the angle of the bend, the length of path on each side of the bend, and the width of the channel 14 combine to exclude such a straight path. However, it is preferred that, as illustrated, the inlet channel 14 is formed with at least two 90° bends. The inlet channel 14 can include one or more segments that lie outside the plane of FIG. 1 . The inlet channel 14 might further include one or more segments that are curved—for example, helical—especially if the cartridge were to have a cylindrical form instead of the rectangular box of the illustrated embodiment.

As previously described, the outlet channel 17 extends in the longitudinal direction along one side wall 18 from the vaporization chamber 22 to the second end 8 of the cartridge 2. At the end of the side wall 18, the air flow path turns through 90° so that air flows in the transverse direction towards the air outlet 16 located near the centre of the second end 8. Between the outlet channel 17 and the air outlet 16, the airflow path passes through means 42 for restricting the airflow. The restriction means 42 may comprise one or more baffles or a mesh that offers resistance to the flow of air therethrough. However, as shown in the illustrated embodiment, the restriction means is preferably a portion of the airflow path that is constricted to form a narrow neck 42. The cross-sectional area of the neck 42 is smaller than the cross-sectional area of the outlet channel 17 and is preferably smaller than the cross-sectional area of the airflow path anywhere else along its length. The cross-sectional shape of the neck and its length when measured along the airflow path will both have some effect on the resistance that the neck offers to the flow of air but the cross-sectional area is the most important factor.

If droplets of liquid have condensed on the walls of the outlet channel 17, the restriction means 42 helps to prevent them flowing to the air outlet 16, where they could leak from the cartridge 2 and enter the mouth of the user or cause drips from the exterior of the cartridge 2. A further feature that helps to prevent droplets of liquid leaking from the air outlet 16 is an internal lip 44 that projects back from the second end 8 towards the first end 6 of the cartridge between the neck 42 and the air outlet 16. Thereby, if the cartridge 2 is oriented such that liquid droplets are flowing towards the second end 8, those droplets cannot reach the air outlet 16 without first changing direction to flow back towards the first end 6. Preferably the lip 44 surrounds the air outlet 16. For ease of manufacture, the air outlet 16, the lip 44 and part of the neck 42 may be formed on a second end cap 46 that is fitted into the second end 8 of the cartridge 2 during the manufacturing process. Inserting the second end cap 46 provides an easy way to control the depth of the airflow path (measured in the longitudinal direction) at the neck 42 and hence, for any given width of the airflow path (measured perpendicular to the plane of FIG. 1 ), to control the cross-sectional area of the neck 42.

The neck 42 is preferably formed such that the airflow through it is in the transverse direction. However, the neck 42 may alternatively or additionally be formed adjacent to the lip 44, where the airflow has at least a component of movement in the reverse longitudinal direction, back towards the first end 6 of the cartridge 2, in order to pass over the lip 44.

Being the most constricted part of the airflow path, the neck or other restriction means 42 also serves to determine the pressure distribution along the airflow path. When the user draws on the mouthpiece 19, it creates low pressure at the air outlet 16, while the air inlet 12 remains substantially at atmospheric pressure. This difference in pressure is distributed along the length of the airflow path, the pressure distribution depending on the resistance to the flow of air at each point. Because the neck 42 offers the greatest resistance to airflow, it defines the region of greatest pressure drop. Providing a neck 42 of appropriate cross-sectional area at the second end 8 of the cartridge is a convenient way to determine the desired pressure within the vaporization chamber 22 and along the outlet channel 17, which helps to regulate the formation of the aerosol in the vapour generating system. The neck or other restriction means 42 also plays a significant role in determining the overall “resistance to draw” of the vapour generating system, which is an important factor when designing such a system.

FIG. 3 schematically shows one possible configuration of a vapour generating system in accordance with the present invention. A vapour generating device 11 houses a power source 50, which provides power to a control circuit 52. The distal end 6 of a cartridge 2 is releasably connected to the vapour generating device 11. There is a mouthpiece 19 at the proximal end 8 of the cartridge 2, which may be attached to or integral with the cartridge 2. Terminals 34 couple the power source 50, via the control circuit 52, to a heater 30 in the cartridge 2. Although the cartridge 2 and vapour generating device 11 are shown connected in an end-to-end configuration, it will be understood that in alternative embodiments of the invention the cartridge 2 could be releasably inserted inside the housing of the vapour generating device 11. In that case, the mouthpiece 19 could be attached to or integral with the vapour generating device 11 rather than the cartridge 2. 

1. A cartridge for a vapour generating system, the cartridge comprising: a first end together defining a longitudinal direction from the first end to the second end; an air inlet; an inlet channel; a vaporization chamber; an outlet channel; and an air outlet; wherein an airflow path extends from the air inlet through the inlet channel to the vaporization chamber, then through the outlet channel to the air outlet; the cartridge further comprising restriction means for restricting airflow between the outlet channel and the air outlet.
 2. The cartridge according to claim 1, wherein the restriction means is a neck in the airflow path, a cross-sectional area of the neck being smaller than a cross-sectional area of the outlet channel
 3. The cartridge according to claim 2, wherein the cross-sectional area of the neck is smaller than a cross-sectional area anywhere else along the airflow path.
 4. The cartridge according to claim 2, wherein the neck is oriented such that the airflow through the neck is in a transverse direction.
 5. The cartridge according to claim 1, wherein the air outlet is located in the second end of the cartridge.
 6. The cartridge according to claim 5, further comprising, between the restriction means and the air outlet, a lip that projects from the second end towards the first end.
 7. The cartridge according to claim 1, further comprising a reservoir configured to store vapour generating liquid to be vaporized in the vaporization chamber.
 8. The cartridge according to claim 7, wherein the outlet channel does not intersect the reservoir.
 9. The cartridge according to claim 8, wherein the outlet channel is adjacent to a longitudinal side wall of the cartridge.
 10. The cartridge according to claim 1, wherein: the airflow path through the inlet channel follows a first transverse direction then turns to enter the vaporization chamber in a second transverse direction.
 11. The cartridge according to claim 10, wherein the inlet channel is convoluted such that the inlet channel provides no straight path from the air inlet to the vaporization chamber.
 12. The cartridge according to claim 10, wherein the inlet channel comprises at least two right-angled bends between the air inlet and the vaporization chamber.
 13. The cartridge according to claim 10, wherein the first transverse direction is opposite to the second transverse direction.
 14. The cartridge according to claim 13, further comprising an airflow diverter element, of which a first surface defines the first transverse direction and a second, opposite surface defines the second transverse direction.
 15. A vapour generating system comprising a vapour generating device and the cartridge according to claim 1, the cartridge being releasably connected to the vapour generating device. 